Light-diffusing shutter for moving-picture machines.



D. F. McGRAW. LIGHT DIFFUSING SHUTTER FOR MOVING PICTURE MACHINES.

APPLICATION FILED OCT. 3 19H.

Patented Jan. 21, 1919.

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641w my I forming a DANIEL FREMONT MCGRAW, OF SAN FRANCISCO, CALIFORNIA, ASSIGNOR GRAPH EDUCATIONAL FILM OF NEVADA.

T0 SAFETY- COMPANY, INC., OF RENO, NEVADA, A CORFOBAATION LIGHT-DIFEUSING SHUTTER FOR MOVING-PICTURE MACHINES.

L Specification of Letters Patent.

Patented Jan. 2 1, 1 3th.

Application filed October 31, 1917. Serial No. 199,454.

'1 '0 all whom it may concern:

Be it known that I, DANIEL FREMONT Mc- GRAW, a citizen of the United States, residing at San Francisco, in ,the county of San Francisco and State of California, have invented certain new and useful Improvements in Light-Diffusing Shutters for Moving-Picture Machines; and I do hereby declare the following to be a full, clear, and exact description of the invention,-such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to translucent, opalescent, or light diffusing shutters either rigid or flexible for moving picture projection machines, and has for .its object to improve the shutters heretofore proposed.

With this and other objects in view the invention consists in the novel details of construct-ion and combinations of parts more fully'hereinafter disclosed and particularly pointed out in the claims.

' Referring to the accompan; ing drawings part of this specification in which like numerals refer to like parts in all the views Figure l is a diagrammatic view partly broken away of a portion of a moving pic ture projecting machine with my shutter in place;

Fig. 2 is a sectional view taken on the line 2-2 of Fig. 1, looking in the direction of the arrows;

Fig. 3 is a view of my improved shutter detached from the machine;

Fig. 4 is a View of the shutter shown in Fig. 3, provided with a modified form of surface; Fig. 5 1s awhich may be view of a two bladed shutter of a modified structure as well as being provided with the surface shown in Fig. 4; and

Fig. 6 is a diagrammatic sectional View of a still further modified form of shutter.

1 indicates any suitable frame work, 2 a crank operating the shaft 3, carrying the gear 4, meshing with the pinion 5 carried by the shaft 6 on which is mounted the gear 7 meshing with the pinion 8 mounted on the shaft 9, carrying the worm 10 meshing with the Worm pinion 11 mounted on the shaft 12, carrying the shutter 13. Said shutter 13 may be provided with three blades as shown in Figs. v1 and 3, or it may be provided. with two blades as illustrated in Fig. 5. Tn all cases the shutteris made of a suitable translucent, opalescent or light dififusing material, and I find a celluloid base suitable for such shutters but of course other well known materials having these characteristics maybe employed if desired. Supposing celluloid to be employed I may provide it with a substantially smooth surface, if the'shutter is to be translucent, or I may provide a plurality of sheets of celluloid 15 and weld or cement them together into a single solid sheet as by a mixture 16 consisting of equal parts of acetone and amylacetate, if the shutter is to be flexible as well as opalescent, or I may grind or otherwise roughen the surface of the shutter if it is to be of a light diffusing charactor.

I prefer to roughen the surface 1'? of the shutter 13 by a grinding, or etching operation, so that when its widest sector 18, as well as its anti-flicker sectors 19 and 20 are opposite the aperture 21. a considerableportion of the light will pass through said sectors and be diffused throughout the room and on the screen very much as would be the case if said sectors were made of the well known ground glass material now used for electric light globes. and for other purposes when it is desired to diffuse the light passing through it.

The effect of thus providing the shutter 13 with a light diffusing surface 17 is to diffuse a portion of the light throughout the room which relieves the objectionable darkness in which moving pictures have been heretofore viewed, while at the same time the objectionable flicker is also eliminated. That is to say, the wider sector 18 of the shutter 13 intermittently shuts off the light from the individual pictures being projected as heretofore, and the anti-flicker or smaller sectors 19 and 20 break up the obscuration in the manner well known, but instead of completely excluding said light from the room and'screen as heretofore, the roughenedor light diffusing surface of the transparent shutter material scatters or diffuses a portion of said light over the room and screen in the intervals during which the pictures are changed, and thus lights up the room to such an extent as to greatly in to the same degree as crease the pleasure of the patrons, while at the same time, the disagreeable flicker heretofore experienced disappears.

- In the somewhat modified form of shutter 30 illustrated in Fig. 4, the larger sector 18 is provided with a.. uniform roughened .or light difi'using surface as was disclosed in connection with Fig. 3, and the central portions 26 of the sectors 19 and 20 are also provided with the same light diffusing surfaces. But the edges or portions 27 and 28 of said sectors 19 and 20 are not roughened are the surfaces 26. In order that these modified light diffusing surfaces shall cut off the same total proportion of ligh't'from the screen as the light difiusing surface 17, l roughen the surfaces and 26 to a somewhat greater extent and I roughen the surfaces 27 and 28 to a lesser extent than said surface 17. The efiect of thus roughening the surfaces of the shutter 30 in the manner just described is to soften thechanges from light to dark in the room, and also to make the pictures more brilliant or distinct on the screen, for the surfaces 25 and 26, out off more light than do the surface 17, and therefore, the contrast on the screen from a maximum to a minimum illumination is greater.

in the still further modified form of the invention disclosed in Fig. 5, only two blades 32 and 33 are provided, and said blades are further provided with surfaces 35, 36, and 37 which act to gradually cut off and diffuse the light in a manner'similar to that just disclosed in connection'with Fig. These said surfaces however, need not be ground on the blades, but their effect may be produced by cementing or Welding different sheets 15 together and incorporating. a light diffusing powder 38 in the said cement or on the surface of said sheets 15. This form of construction also produces a flexible shutter. I

It will now be clear that in all the forms of the invention the light-instead of being suddenly out off at brief intervals from the screen is partially diffused throughout the room and that therefore the objectional darkness heretofore experienced is eliminated.

It is obvious that those skilled in the art may vary the details of without departing from the spirit of the invention, and therefore,.l do not wish to be limited to theabove disclosure except as may be required by the claims.

/Vhat I claim is 1. A shutter for moving picture machines comprising a plurality of roughened light transmitting and light diffusing blades the edge portions of which are roughened to a lesser degree and are adapted to transmit more light than the middle portions, substantially as described.

2. A shutter for moving picture machines comprising a plurality of light transmitting and light diffusing blades one of which is provided with a roughened surface adapted to transmit and diffuse light equally substantially over its entire surface, while others of said blades are provided with roughened surfaces adapted to transmit more light through their edge portions than through their middle portions, substantially as ;lescr'ibed.

the constructlon in presence of two witnesses.

DANIEL FREMONT hloGRAW.

Witnesses:

W. T. Hess, 

